Scotch yoke



Jan. 2, 1945. DE wr'r'r cLAusEN SCOTGH YOKE Filed Sept. 25, 1943 jkl/enfer enI M' rm c/qormsa 5 Patented Jan. 2, 1945 `UNIYTED- STATES PATENT 'OFFICE De Witt GlausemrAkron, Ohio; assignorfto Lucien l I." Yeomans,` Inc., Chicago,` Ill.', a* corporation of Illinois Application September 23, lilflpserial No. 503,503 1 3 Claims. (Clair- 50) The invention relates to` Scotch yokesandhas as its general aim the provision of a new and improved-device` of` this character in which power loss dueto friction issubstantially eliminatedand wear is` minimized whereby the device has high ,efliciency-and long life.

`Anfoloject-of thefinvention is to provide a Scotch yokeY type `of` mechanical movement which embodies novel means between'the driving and thedriven members for* minimizing the frictional resistance created by the relative movementsof theseyparts.-

More particularlystated, anobject of the in- .vention is?. to provide a device offthis nature in ,whichv antifriction members interposed between thecrank actuated block andthe crosshead` or yoke are supportedin freeiioating `relation to the block and' to the crosshead for independent movement relative thereto.

While the invention is susceptible of various modications and alternative constructions I have shown inthe drawing and will herein describe in` detail, the preferred embodiment, but

itisto be understood that I do not thereby intend `tollimit the invention to the specic form disclosed, but intend to cover all modifications and alternativeconstructions falling within the spirit andf scope of the invention as expressed in the `appended claims;

The present invention is shown as being embodiedin a Scotch yoke arranged as the driving connection between a power driven crank I and 'fthe vspaced axially alined pistons Il of an opposed piston type pump. Thisarrangement is shown merely by way of example, since it will be evident that the presentldevice may be emi is disposed in the slotgof the crossheadzand has bearings `Il preferably beingfinterpo-sed therebe`` tween. As may best,` be seenin Fig. 1, the block iiattened side faces lropposingjat faces l!)` on wear plates secured to.thecrossheadto` extend along-the lsides t l 3` thereof` within the slot.

. r lnthe operationof thesedeviceathe circular movement of the'crankarm orl pin I6; and block l5` thereon will produce al straight line recipro- `catory pmovementlof thev crosshead I4 and `pistons Il; together with'a reciprocatory` movement of the block I5 relative to the crosshead` in a` direction perpendicular-to the aforesaid. straight line .-reciprocation. `The power` loss dueto friction..` and the comparatively heavyrwear which introducesundesirable clearanceor play between theh block and the crosshead,4 arerdisadvantages which have beenrinherent in@ devices of this character. i r p The present invention` substantially `minimizes both of these factors of power lossand weartin a simple and highly eicient manner.` To this end the invention contemplatesthe' interposi-` tioning between the blocksurfaces I8' andx|9 `on the block `and' cross headrespectively of antifriction elements in' the formnof` a `unitary asbodying centrally` open side framesl23`supporting sembly` mounted or supported" in freej iiloating relationtobothitheV block and crosshea'dso as to 30p be capable of independentV unitary movement.

In the present'embodimentasfshown in Fig. 1 the dimensions-of theblock between its surfaces l8 is i substantially: less thanl the `distance between the surfaces I9 on therw'ear plates 20; ,In-its centered position between the` wear plates this dimensional relation provides spaces betweenthe block sides andeachof the wear-plates to receive bearingelementsZl of an antifrictionunit` 22;

Thevantifriction unit 2^2lis shown' herein as emtherebetweenl elongated plate.. members 2li@` each of" which has` a @riesci-pockets formedrtheren v to receive such'antifriction elements 2| as the ployed in connection with many other mecha`- nisms. In thisembodiment, however, the pistons` l l1 'arevreciprocally mounted in cylinder blocks I2 `and have their inner or adjacent ends rigidly connected 4vas at |2ai centrally with the elongated sides,|3 ofvagslotted crosshead or yoke |4` that extendsfperpendicularly to the axes of the pistons. A block I 5 is;` suitably supported on an arm or pin I E of the crank I0, suitable roller cylindrical rollers herein illustrated. The plates 24 are accurately spaced apart properly to dist pose the roller elements between the side faces |8on the block and the opposed faces i9 on `the Wear plates. The side frames are so dimensioned that their side edges as indicated at 25 will extend beyond the surfaces I9 on the wear plates to prevent `lateral or sidewise displacement of `the antifriction` unit. The length of each set of antifriction rollers is preferably suoli as to provide bearing means which is at least coextensive with the length of the block surfaces i8 in any position of the block.

In considering the operation of the device it will be presumed that the crank I is rotating clockwise as seen in Fig. l. One complete revolution of the crank arm l1 will produce one complete reciprocatory stroke of the pistons ll and one complete reciprocatory stroke of the block I5 with respect to the crosshead. When the axis of the crank arm IB is alined with the axes of the pistons Il the pistons will be at one end or the other of a stroke. It is at this point that the thrust load transmitted fro-m the block to the crosshead shifts from the'antifriction rollers on Y one side of the block to those on the other side. At this same instant, however, the block is at the intermediate point of its reciprocatory movev ment and is traveling at its greatest rate of speed. Consequently thesudden imposition of the thrust force on one or the other of the sets of antifriction rollers occurs when the rollers are traveling at their greatest rate of speed. The rollers are, therefore,l able most effectively to take the thrust force imposed thereon. It will be noted, furthermore, that the antifriction elements are under full thrust load at the transition points of their reciprocatory movementas produced by the recprocation ofthe block relative to the crosshead and that they approach and leave these transition points gradually and without shock. These relationships materially increase the life, operating and wear resistingl characteristics of the" present device overprior devices of this character.

Inoperation the antifriction unit will tend to seek a centered position between the ends of the block and crosshead even though the unit may have settled somewhatfby its weight when the device was idle. lIt is` preferred, however, to limit the possible descending movement by such means Vas a bar 26 extending between the plates 24 across the upper side of the crosshead. The first revo1u' tion of the crank will restore the antifriction unit to its centered position.

It will be evident from the foregoing that av Scotch yoke device has been provided which hasr new and improved'means for transmitting the thrust force between the block and the crosshead. Since the free floating antifriction unit is independent of the block and crosshead it is not forced t0 follow the relative movements of these parts in the same fashionv as if it were connected with one or the other. As a result the antifriction unit is free for self-adjustment to its most effective operating position. f

I claim as my invention:

1. In a Scotch yoke, the combination of a slotted cross head mounted for reciprocation and having opposed vsurfaces within the slot extending transversely to the line of reciprocation thereof, a driving block mounted in said slot between said surfaces and having movement through a circular path, a. frame having side portions rigidly cof united and disposed adjacent opposite lateral sides of said block, flat supporting members carried by said side portions of said frame and extending one between each opposite side of said block and the adjoining opposed surface on said cross head, and two series of 'antifriction elements carried by respective ones of said supporting members and 'located respectively on flat planes between the` opposite sides of said block and said cross head, the rigid joining of the side portions of said frame carrying the two series of antifriction elements serving to compel bothrseries to move in unison with each other longitudinally of said slot in the course of movement of said block within said slot.

` 2. In a Scotch yoke, the combination of a slotted cross head vmounted for reciprocation and having opposed surfaces within the slot extending transversely to the line of reciprocation there-l of, a driving block mounted in said slot Vbetween said surfaces and having movement through a circular path, and unitary antifriction means for transmitting thrust forces from said block tosaid cross* head includinga frame, means for locating said frame in free floating relation to saidcross head and block in the planev of their relative movements, said frame having lateral sideportions rigidly joined together and lying vadjacent opposite lateral sides of said block', supporting ymeans carried by said side portions of saidframe to extend between said opposite sides of said block and the adjoining opposed surfaces on said cross head, and a series of antifriction elements carried loy said supporting means and interposed between said b-lock and cross head, each said series being longer than the `surface on said block engaged thereby and shorter than said slot.

3. In a Scotch yoke, the combination of a slotted'cross head mounted for. reciprocation and having opposed surfaces within. the slot extending transversely to the line of reciprocation thereof,

between the same and located between the opposed side surfaces of said block and slot, and two series of antifriction elements carried by said supporting means at respective yopposite sides of said block between the Opposed surfaces of the latter and of said slot, each of said series being longer than the surface on said blocken- DE WITT. CLAUSEN.v 

